The invention relates to organic waste gasification processing using an oxygen-starved (O2-starved) gasification process, and is also directed toward deriving alternative energy sources from by-products produced by such a process.
Current municipal and other waste production is increasing in volume and is expected to continue increasing. Increased reliance is being placed on waste disposal methods that eliminate waste without requiring the use of scarce landfill space. One such disposal method that is known and widely used is a xe2x80x9cmass burnxe2x80x9d waste incinerator.
Another disposal method that is known gasifies the organic waste without burning it. An example of such a method is disclosed in the present inventor""s U.S. Pat. No. 4,941,415, which is incorporated by reference. With the waste gasification method, organic waste is first converted into a gaseous effluent by heating the waste at a high temperature and in an O2-starved chamber. The resulting O2-deficient effluent is released from the chamber and then mixed with an O2-containing gas so that the effluent can be combusted to provide a cleaner emission into the atmosphere. The O2-enriched effluent is combusted using a flame burner, and the resulting exhaust is released into the atmosphere through a stack.
A way that the O2-deficient effluent has been mixed with the O2-containing gas in the past, which is disclosed in the xe2x80x2415 Patent, uses a hollow ring that surrounds the path of effluent flow and introduces the O2-containing gas into the path at a single cross-section. The effluent, now O2-enriched, flows upward where a set of flame burners direct a xe2x80x9cropedxe2x80x9d flame upward into an inverted ceramic cup. The ceramic cup provides a high temperature environment for combustion. The ceramic cup also slows the effluent""s flow to achieve a more complete combustion.
For waste disposal methods that avoid the use of landfill space but which produce emissions into the atmosphere, there is a need to provide systems that produce cleaner emissions. There is also a need to provide for waste disposal system designs that minimize building costs while meeting the individual needs of the waste producer (for example, producers with different volumes of waste and space requirements). Further yet, there is also a need to provide alternative fuel sources.
In one aspect, the invention provides for an alternative energy source that is derived from an O2-starved effluent produced when organic waste is subjected to an O2-starved gasification process. The energy source is used to power a variety of secondary applications.
In one embodiment, the O2-deficient effluent serves as the energy source that could be used, for example, in a combustion engine. This energy source could be stored in a transportable tank prior to being used, so that the secondary application could be located at a remote site. In another embodiment, the O2-deficient effluent is mixed with an O2-containing gas, and the mixed effluent serves as the energy source that could be used, for example, in a machine that produces steam, in a reverse-refrigeration process, or in a grain dryer. In another embodiment, mixed (that is, O2-enriched) effluent is combusted to produce heat that serves as the energy source that could be used, for example, in a hot-water heater or to smelt aluminum.
In another aspect, the invention is an organic waste gasification processor whose emissions into the atmosphere are cleaner. This gasification processor has a primary gasification chamber for receiving waste and for producing an effluent by an O2-starved process. The gasification processor also has a mixing chamber with an effluent pathway extending therethrough. The mixing chamber receives the effluent produced by the primary gasification chamber and mixes it with an O2-containing gas. The O2-containing gas is introduced into the effluent pathway at a plurality of entry points positioned along most of the length of the portion of the effluent pathway that extends through the mixing chamber. The length over which the O2-containing gas is introduced into the pathway may be, for example, about eight feet in length. Finally, a secondary combustion chamber receives and incinerates the mixed effluent.
In one embodiment, the mixing chamber has an inner jacket that surrounds the effluent pathway. The inner jacket has a plurality of holes arranged in a scattered array that serve as the entry points into the effluent pathway. An outer jacket surrounds the inner jacket and forms a gas gap between the two jackets. The O2containing gas to be introduced into the mixing chamber is first received in the gas gap. The O2-containing gas then flows through induction tubes that extend through the holes in the inner jacket and into the effluent pathway. Pillowed insulation on an inside surface of the inner jacket, which protects the jackets of the mixing chamber from excessive heat, additionally creates turbulence in, and hence reduces the flow rate of, the effluent passing through the mixing chamber.
With the entry points of the O2-containing gas spread over an increased length of an effluent pathway, improved mixing of the effluent with an O2-containing gas occurs that what was possible with the prior art (for example, the design disclosed in the xe2x80x2415 Patent). Also, the manner by which the O2-containing gas is introduced into the effluent pathway and the irregular surface of the effluent pathway at the point of mixing, both add turbulence into, and slow, the effluent flow, thereby enhancing the effluent mixing process. This is achieved without the need for the ceramic cup used in the prior design disclosed in the xe2x80x2415 Patent to slow effluent flow. One or more of increasing the retention time within the effluent pathway, increasing the mixing length, and increasing the distance between the point of mixing and final effluent combustion provides a more thorough combustion of the mixed effluent.
In yet another aspect, the invention is an expandable waste gasification system that combines multiple O2-starved primary gasification chambers in a waste gasification system. The system has a single secondary combustion chamber and one or more mixing chambers that mix(es) the effluent produced by the multiple primary chambers with an O2-containing gas. The expandable nature of the multiple primary gasification chamber design enables a gasification system design to be easily tailored to an individual or community""s needs. As such, the cost of building systems that meet a waste producer""s individual needs is minimized.
Advantages of the invention include one or more of the following. Virtually complete elimination or reuse of solid and liquid wastes is achieved. From the wastes that are initially loaded, the system produces recyclable glass, aluminum, other metals, and a fine, inert ash, as well as the combustible gas. The gas may be combusted in a manner that provides for a cleaner emission into the atmosphere, or it may be used to derive an alternative energy source. The latter conserves traditional energy sources that would otherwise be used to power a secondary application. As a result, an attractive and environmentally friendly alternative to disposing waste in landfills and xe2x80x9cmass burnxe2x80x9d incinerators is provided. Additional advantages of the invention will be apparent from the following description and claims.